NASSAU COUNTY, Fla. – A former Yulee Middle School softball coach has resigned. The Nassau County Sheriff’s Office said it’s investigating him, though it’s unclear why.

The former coach, who was also a math teacher, is not facing criminal charges, therefore News4Jax has chosen not to identify him.

Students received a note from the principal saying the teacher resigned in early February. A statement from the Nassau County School District reads:

"The district is aware that the Sheriff’s Office has an open investigation concerning (the teacher) and has cooperated fully with the investigation. The district does not comment on pending investigations.”

A student in the teacher’s class, who asked to remain anonymous, said he was surprised.

“I was just confused," the student said. "My class was just confused about what was going on because everyone in my class like him. He was the best teacher that I have.”